Occurrence, abundance, and characteristics of microplastics in marine fish from the Cox’s Bazar coast, Bay of Bengal

Abstract

Microplastic contamination in marine ecosystems has emerged as a growing environmental concern, yet information on commercially important fish species from the Bay of Bengal remains limited. This study investigated the occurrence, abundance, and characteristics of microplastics in the gill and gastrointestinal tract (GIT) tissues of eight widely consumed marine fish species collected from the Cox’s Bazar coast of Bangladesh. A total of 40 specimens were analyzed using alkaline digestion, microscopic identification, and polymer characterization via ATR-FTIR spectroscopy. Microplastics were detected in 77.5% of gill samples and 82.5% of GIT samples, with a total of 172 particles identified. The mean abundance was 2.55 ± 0.21 items per sample in gills and 2.82 ± 0.37 items per sample in GIT. Fibers were the dominant morphotype (91.86%), followed by fragments (8.14%). Blue-colored particles were most prevalent (40.69%), with particles in the 501–1500 µm (36.62%) and 151–500 µm (30.81%) size classes being the most abundant. ATR-FTIR analysis of a representative subset of particles revealed that polyethylene (39.53%) and polypropylene (30.23%) were the most common materials, with polyester also contributing notably (18.60%). Microplastic abundance showed no significant relationship with fish morphometric parameters. Variations among species suggested possible influences of feeding behavior and habitat, although these observations should be considered exploratory because of the limited sample size. The predominance of fibrous particles and common packaging-related polymers suggests multiple anthropogenic sources, including fisheries and domestic waste. These findings emphasize the need for improved waste management, reduction of plastic use in fisheries, and stricter regulation of synthetic discharges to mitigate microplastic contamination in coastal marine environments of Bangladesh.